In the scandal that rocked the Raj in 1891, a notorious curio-dealer from Simla offered to sell the world’s largest brilliant-cut diamond to the Nizam of Hyderabad. If the audacious deal had gone through, the merchant would have been set up for life. But the transaction went horribly wrong. The Nizam accused him of fraud, triggering a sensational trial in the Calcutta High Court that made headlines around the world. The dealer was Alexander Malcolm Jacob, a man of mysterious origins and colourful infamy. He was India’s most successful purveyor of precious stones and was rumoured to be “rich almost beyond the dreams of Aladdin”. Hailed as a celebrity in his own lifetime, he was the inspiration for the shadowy Lurgan Sahib in Rudyard Kipling’s Kim. A confidant of viceroys and maharajahs, he dabbled in magic and was a player in the Great Game. Yet he died in obscurity, carrying many of his secrets to his grave. In this meticulously researched account of Jacob’s life, John Zubrzycki, much fêted for The Last Nizam, reconstructs events through long-lost letters, court records and annotations on secret files, bringing us a riveting study of a man whose obituary in a leading daily fittingly described him as the most “romantic and arresting figure in our time”.

‘A lucky venture, a lucky venture! Plenty of rubies, plenty of emeralds! You should thank God for having brought you to such a rich country!” The words that greeted Vasco da Gama when he reached Calicut in 1498, might well have applied to Jacob as he took up Burne’s advice and threw himself into the gem trade. For someone pursuing a career built on buying and selling precious stones there was no better place to start than India.

The stories and legends of India’s wealth are as old as the great Hindu epics. The Mahabharata referred to northern tribes who sent lumps of gold to Yudhishtira collected by ferocious giant ants who attacked anyone who dared to enter their territory. The Ramayana described the holy city of Ayodhya as being “filled with merchants and artificers of all kinds; gold, precious stories, and jewels were there found in abundance; everyone wore costly garments, bracelets, and necklaces”.

In da Gama’s day, India’s mines were still producing vast quantities of diamonds, sapphires, rubies, hyacinths and amethysts that were being traded